Method of operating a vehicle

ABSTRACT

A method of operating a vehicle includes navigating the vehicle along a path, collecting a set of navigation parameters of the vehicle from at least one of a sensor, a global positioning system, or an inertial reference system, determining a set of statistical uncertainties related to at least some navigation parameters in the set of navigation parameters, and associating a set of statistical weights to the at least some navigation parameters.

TECHNICAL FIELD

The disclosure generally relates to methods of operating vehicles, suchas aircraft, including the collection of navigational parameters of thevehicle during operation.

BACKGROUND

In contemporary vehicles including aircraft, numerous data sources canbe considered for determining desired navigational parameters, such asposition, speed, direction, altitudes, paths, or suitable waypoints, orfor estimating time of arrival and fuel burned during operation, etc.Accuracy and reliability of such determinations are important for pathadjustments or updates, as well as for traffic control relating to othervehicles that may be nearby.

BRIEF DESCRIPTION

In one aspect, the disclosure relates a method of operating a vehicle.The method includes navigating the vehicle along a path, collecting aset of navigation parameters of the vehicle from at least one of asensor, a global positioning system, or an inertial reference system,determining a set of statistical uncertainties related to at least somenavigation parameters in the set of navigation parameters, associating aset of statistical weights to the at least some navigation parametersbased on the set of statistical uncertainties, determining anavigational solution for the vehicle based on the set of statisticalweights, and operating the vehicle in accordance with the navigationalsolution.

In another aspect, the disclosure relates to a method of operating anaircraft. The method includes navigating the aircraft along a flightpath, collecting a set of navigation parameters of the aircraft from atleast one of a sensor, a global positioning system, or an inertialreference system, determining a set of preliminary solutions for the setof navigation parameters by applying a Kalman filter, determining a setof errors for the set of preliminary solutions, determining, via acovariance matrix, a set of statistical uncertainties for the set ofpreliminary solutions based on the set of errors, associating a set ofstatistical weights to the set of preliminary solutions based on the setof statistical uncertainties, forming a navigational solution for theaircraft by blending the set of preliminary solutions based on the setof statistical weights, and operating the aircraft in accordance withthe navigational solution.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1 is a top-down schematic view of a portion of a vehicle in theform of an aircraft in accordance with various aspects described herein.

FIG. 2 is a schematic view of navigational parameters of the aircraft ofFIG. 1 in accordance with various aspects described herein in the formof a position of the aircraft.

FIG. 3 is a schematic view of a navigational solution based on thenavigational parameters for the aircraft of FIG. 1 in the form of ablended position of the aircraft in accordance with various aspectsdescribed herein.

FIG. 4 is a schematic top view of the aircraft of FIG. 1 illustrating acurrent flight path and a modified flight path in accordance withvarious aspects described herein.

FIG. 5 is a flowchart illustrating a method of operating the aircraft ofFIG. 1 in accordance with various aspects described herein.

FIG. 6 is a flowchart illustrating another method of operating theaircraft of FIG. 1 in accordance with various aspects described herein.

DETAILED DESCRIPTION

Aspects of the present disclosure are generally directed to a method ofoperating a vehicle and including functions, mechanisms, or operationssuch as navigation. For purposes of illustration, the present disclosurewill be described in the context of a flight management system in anaircraft environment. It will be understood, however, that thedisclosure is not so limited and may have general applicability innon-aircraft applications, non-vehicular applications, or other mobile,land-based, aqueous-based, or similar applications.

Aspects of the disclosure will be described in the general context of amethod that can be implemented in one aspect by a program productincluding machine-executable instructions such as program code, forexample, in the form of program modules. Generally, program modulesinclude routines, programs, objects, components, data structures,algorithms, etc. that have the technical effect of performing particulartasks or implement particular abstract data types. Machine-executableinstructions, associated data structures, and program modules representexamples of program code for executing the method disclosed herein.Machine-executable instructions can include, for example, instructionsand data, which cause a general purpose computer, special purposecomputer, or special purpose processing machine to perform a certainfunction or group of functions.

As used herein, “a set” can include any number of the respectivelydescribed elements, including only one element. All directionalreferences (e.g., radial, axial, proximal, distal, upper, lower, upward,downward, left, right, lateral, front, back, top, bottom, above, below,vertical, horizontal, clockwise, counterclockwise, upstream, downstream,forward, aft, etc.) are only used for identification purposes to aid thereader's understanding of the present disclosure, and do not createlimitations, particularly as to the position, orientation, or use of thedisclosure. Connection references (e.g., attached, coupled, connected,and joined) are to be construed broadly and can include intermediatemembers between a collection of elements and relative movement betweenelements unless otherwise indicated. As such, connection references donot necessarily infer that two elements are directly connected and infixed relation to one another. The exemplary drawings are for purposesof illustration only and the dimensions, positions, order, and relativesizes reflected in the drawings attached hereto can vary.

Also, as used herein, while sensors can be described as “sensing” or“measuring” a respective value, sensing or measuring can includedetermining a value indicative of or related to the respective value,rather than directly sensing or measuring the value itself. The sensedor measured values can further be provided to additional components. Forinstance, the value can be provided to a controller module or processor,and the controller module or processor can perform processing on thevalue to determine a representative value or an electricalcharacteristic representative of said value.

FIG. 1 depicts one exemplary vehicle 1 in the form of an aircraft 10.The aircraft 10 can include one or more propulsion engines 12 coupled toa fuselage 14, a cockpit 16 positioned in the fuselage 14, and wingassemblies 18 extending outward from the fuselage 14. A plurality ofaircraft systems 20 that enable proper operation of the aircraft 10 (orsubsystems thereof) can be included, such as, but not limited to, aflight control computer 22, and a communication system having a wirelesscommunication link 24. The exemplary aircraft 10 has been illustrated inthe form of a commercial aircraft. It is contemplated that aspects ofthe disclosure can be used in other environments including, but notlimited to, fixed-wing aircraft, rotating-wing aircraft, personalaircraft, or other manned or unmanned vehicles.

The plurality of aircraft systems 20 can reside within the cockpit 16,within a dedicated electronics and equipment bay 25, or in otherlocations throughout the aircraft 10 including the engines 12. Suchaircraft systems 20 can include but are not limited to: an electricalsystem, an oxygen system, hydraulics and/or pneumatics system, a fuelsystem, a propulsion system, navigation systems, flight controls,audio/video systems, an Integrated Vehicle Health Management (IVHM)system, Onboard Maintenance System, Central Maintenance Computer, andsystems associated with the mechanical structure of the aircraft 10. Avariety of aircraft systems 20 have been illustrated for exemplarypurposes and it will be understood that they are non-limiting example ofschematically representative systems that can be included in theaircraft 10.

The cockpit 16 can include at least one display 21 configured to displaya variety of parameters including navigational data, flight time, fuelconsumption, weather conditions, pilot advisories, current heading, orthe like. The display 21 can include an electronic viewable screen, andcan also be configured to receive user input via a touchscreen,keyboard, buttons, dials, or other input devices.

The flight control computer 22, which can include a flight managementcomputer, can among other things, automate the tasks of piloting andtracking the flight plan of the aircraft 10. The flight control computer22 can include or be associated with any suitable number of individualmicroprocessors, power supplies, storage devices, interface cards, autoflight systems, flight management computers, and other standardcomponents. The flight control computer 22 can include or cooperate withany number of software programs (e.g., flight management programs) orinstructions designed to carry out the various methods, process tasks,calculations, and control/display functions necessary for operation ofthe aircraft 10. The flight control computer 22 is illustrated as beingin communication with the plurality of aircraft systems 20, the wirelesscommunication link 24, and the display 21. It is contemplated that theflight control computer 22 can aid in operating the aircraft systems 20and can send and receive information from the aircraft systems 20.

The wireless communication link 24 can be communicably coupled to theflight control computer 22 or other processors of the aircraft totransfer flight data off the aircraft 10. Such a wireless communicationlink 24 can be any variety of communication mechanism capable ofwirelessly linking with other systems and devices and can include, butis not limited to, packet radio, satellite uplink, Wireless Fidelity(WiFi), WiMax, Bluetooth, ZigBee, 3G wireless signal, code divisionmultiple access (CDMA) wireless signal, global system for mobilecommunication (GSM), 4G wireless signal, long term evolution (LTE)signal, Ethernet, or any combinations thereof. Further, the wirelesscommunication link 24 can be communicably coupled with the flightcontrol computer 22 through a wired or wireless link. Although only onewireless communication link 24 has been illustrated, it is contemplatedthat the aircraft 10 can have multiple wireless communication linkscommunicably coupled with the flight control computer or other onboardcomputing device receiving flight information. Such multiple wirelesscommunication links can provide the aircraft 10 with the ability totransfer flight data off the aircraft 10 in a variety of ways such as bysatellite, GSM, or WiFi.

Further, one or more sensors 26 can be provided on or within theaircraft 10 to obtain flight data during operation of the aircraft 10including, but not limited to, latitude, longitude, altitude, velocity,acceleration, angular rate, heading, bearing, or the like. The one ormore sensors 26 can be included in any aircraft system 20, includingbeing communicatively coupled to any aircraft system 20. The one or moresensors 26 can also be capable of sensing and providing bothenvironmental and aircraft data. As used herein, “environmental data”can include or refer to, in not limiting examples, as sensed or measuredweather or air data including temperature, pressure, relative humidity,icing, turbulence data, other data related to the environmentalconsiderations or factors external to the aircraft, or the like. Also,as used herein, “aircraft data” can include or refer to, in not limitingexamples, as sensed or measured data from any aircraft system 20including navigational data, braking hydraulics, speed and performanceparameters including deceleration data, acceleration data, landingperformance data, take-off performance data, derated thrust data, runwaycondition parameters, aircraft weight or class, attitude or location,fuel temperature, or the like. The sensors 26 can also be capable ofintegrating such information with a physical location of where the datawas obtained as well as a time stamp of when such information wasobtained. For example, the environmental or aircraft data, e.g.acceleration or angular rate data, can include an association with acoordinate or set of coordinates, or the like, indicating where thesensing or measuring occurred.

The sensors 26 can be located in any suitable location on or within theaircraft 10, such as the nose, tail, engine 12, wing assembly 18,elsewhere on the fuselage 14 or within the cabin or cockpit, or thelike, or any combination thereof. Any number of sensors 26 can beutilized. The sensors 26 can be operably coupled for communication withthe flight control computer 22, the flight management system 28, oranother controller onboard the aircraft 10 to provide the aircraft 10with such flight data. It is also contemplated that the sensors 26 canbe communicatively coupled with the wireless communication link 24 toallow the information obtained by the sensors 26 to be relayed off theaircraft 10, such as to a ground station or another aircraft (notshown), without the flight control computer 22 or flight managementsystem 28. Additionally or alternatively, aircraft data can be obtaineddirectly from the aircraft systems 20 and relayed off the aircraft 10.

In another example, the flight data computer 22 can receive data fromanother aircraft. The program can include a computer program productthat can include machine-readable media for carrying or havingmachine-executable instructions or data structures stored thereon. Suchmachine-readable media can be any available media, which can be accessedby a general purpose or special purpose computer or other machine with aprocessor.

The aircraft 10 can further include a flight management system 28 incommunication with the flight control computer 22. It will be understoodthat the flight management system 28 can be hard wired to the flightcontrol computer 22 or may communicate in any suitable manner with theflight control computer 22 including via wireless communication.

A global positioning system (GPS) 30 and an inertial reference system(IRS) 40 can also be provided in the aircraft 10. The global positioningsystem 30 can include an antenna (not shown) configured to communicatewith a set of satellites or at least one communication network. Theinertial reference system 40 can include sensing components includinggyroscopes, accelerometers, or magnetometers, in order to determine aposition, velocity, acceleration, angular rate, orientation, or thelike, of the aircraft 10. Either or both of the GPS 30 and IRS 40 cangenerate, output, or otherwise communicate data, including data relatingto the position, velocity, acceleration, angular rate, orientation, orthe like, of the aircraft 10. In non-limiting examples, such data can beoutput or communicated to the display 21, flight control computer 22,the flight management system 28, or the like. In addition, multiple GPSs30 or IRSs 40 can be provided for measurement redundancy or improvedaccuracy or availability.

While not shown for brevity, it is further contemplated that a system 20of the aircraft 10 can include a distance measuring equipment (DME)navigation radio or a very high frequency (VHF) omni-directional ranging(VOR) navigation radio. Such a DME or VOR can include sensors 26 in theform of antennas configured to receive distance and directional bearingdata from associated DME or VOR ground stations, such as navigationalaids. The distance and bearing information received from such groundstations can be processed or otherwise utilized to determine a positionof the aircraft 10. In non-limiting examples, such data can be output orcommunicated to any or all of the display 21, flight control computer22, flight management system 28, or the like, including for navigationor other operation of the aircraft 10. In addition, multiple DMEs orVORs can be provided for measurement redundancy or improved accuracy.

During operation, a system 20 of the aircraft 10, the flight controlcomputer 22, or the flight management system 28 can receive informationor flight data from other aircraft systems 20, the one or more sensors26, the GPS 30, or the IRS 40. The flight data can include informationabout the location, motion, orientation, or the like, of the aircraft10. Such flight data can be received by a controller module having aprocessor and memory, displayed to a user such as on the display 21,transmitted to another aircraft or a ground station (not shown) via thewireless communication link 24, utilized by the flight control computer22 for calculations or updates relating to other aircraft operationssuch as fuel calculations, engine efficiencies, flight path or timingupdates, or cost estimates, in non-limiting examples, or the like.

One example of such flight data will be described in further detail withreference to FIGS. 2 and 3. Referring now to FIG. 2, a coordinate system50 is illustrated with plotted navigational parameters from at least onesource on the aircraft 10. The at least one source can include the oneor more sensors 26, the GPS 30, the IRS 40, or any other aircraft system20 (FIG. 1). In the example shown, the coordinate system 50 is in theform of a latitude-longitude reference system with a first axis 51representing longitude and a second axis 52 representing latitude. Anysuitable coordinate system for any suitable vehicle can be utilized,such as an Earth-centered, Earth-fixed (ECEF) X/Y/Z reference systemmade relative to the aircraft 10, or a latitude/longitude/altitudereference system, in non-limiting examples.

A set of navigation parameters 60 is plotted on the coordinate system50. The set of navigation parameters 60 can include any data or statevariables relating to navigation of the aircraft 10 including, but notlimited to, a current or past position, velocity, acceleration,orientation, heading, bearing, or any combination thereof. In theillustrated example, the set of navigation parameters 60 includes afirst position 61 shown with a star, a second position 62 shown with arectangle, and a third position 63 shown with a triangle. The positions61, 62, 63 can be obtained from any or all of the sensors 26, GPS 30,IRS 40, or the like. For example, it is contemplated that the positions61, 62, 63 can each be obtained from a single sensor 26 or source, suchas the IRS 40. In another example, the positions 61, 62, 63 can beobtained from three separate inertial reference systems (or redundanciesthereof) on the aircraft 10, each providing an independent output. Instill another example, the IRS 40 can provide the first position 61, theGPS 30 can provide the second position 62, and a sensor 26 can providethe third position 63.

The set of navigation parameters 60 can include errors or uncertaintiesfrom a variety of sources, including measurement errors or calibrationerrors. In the illustrated example, the positions 61, 62, 63 representthe position of the aircraft 10 plotted on the coordinate system 50. An‘x’ symbol denotes a “true” position 65 of the aircraft 10, i.e. theposition that would be measured in the event of zero measurement erroror uncertainty. Table 1 below illustrates one non-limiting example ofthe positions 61, 62, 63 and the true position 65. While Table 1 isshown having latitude/longitude with significant digits, anyrepresentation of position 61, 62, 63 data or representation can beincluded in aspects of the disclosure.

TABLE 1 First position (61) N41.28626984 W122.59631330 Second position(62) N41.21987530 W122.62962310 Third position (63) N41.35301667W122.55768753 True position (65) N41.25296125 W122.61296820

A set of preliminary solutions 70 can be determined, including beingcomputed, based on at least some navigation parameters in the set ofnavigation parameters 60. As used herein, “preliminary solution” willrefer to a value that represents an updated navigation parameter byaccounting for errors or uncertainties that may be associated with thatnavigation parameter. Stated another way, “preliminary solution” canrepresent an updated, modified, altered, or otherwise “corrected”navigational parameter. In non-limiting examples, the set of preliminarysolutions 70 can be determined or computed by hand, by the flightmanagement system 28, by the flight control computer 22, or by any othersuitable aircraft system 20, or the like, or any combination thereof.

The set of preliminary solutions 70 can account for errors oruncertainties present in the set of navigation parameters 60. In onenon-limiting example, a Kalman filter can be applied to at least some ofthe set of navigation parameters 60 to obtain the set of preliminarysolutions 70. Still referring to FIG. 2, the corresponding set ofpreliminary solutions 70 includes a first preliminary solution 71 shownwith a star, a second preliminary solution 72 shown with a rectangle,and a third preliminary solution 73 shown with a triangle.

In the example shown, a Kalman filter is applied to the first, second,and third positions 61, 62, 63 to obtain the corresponding preliminarysolutions 71, 72, 73. For example, the Kalman filter can operate onsensor 26 measurements from anywhere on the aircraft 10 or a system 20thereof, including the GPS 30, IRS 40, a DME or VOR as described above,or the like, to provide correction to the set of navigation parameters60.

The preliminary solutions 71, 72, 73 can still include errors oruncertainties, as indicated by their relative deviation or distance fromthe representative true position 65. A set of errors 80 can bedetermined or computed, such as via the Kalman filter, for each in theset of preliminary solutions 70. In non-limiting examples, the set oferrors 80 can be determined or computed by hand, by the flightmanagement system 28, by the flight control computer 22, or by any othersuitable aircraft system 20, or the like, or any combination thereof.

The set of errors 80 is visually represented in FIG. 2 by arrows drawnfrom each position 61, 62, 63 to each corresponding preliminary solution71, 72, 73. Larger errors are represented by larger arrows, and smallererrors are represented by smaller arrows. The set of errors 80 canrepresent a change or correction in position as a result of computingthe preliminary solution (e.g. an adjustment to correct for measurementerrors). In the example shown, the set of errors 80 includes a firsterror 81, a second error 82, and a third error 83 corresponding to aKalman-filter output of position error estimates for each of thepreliminary solutions 71, 72, 73. Table 2 below represents onenon-limiting numerical example of the set of errors 80 corresponding toeach position obtained from the IRS 40 in Table 1. Each error in the setof errors is represented by values in nautical miles (NM) with positivevalues referenced to “north” and “east.” It will be understood thatnegative values correspond to “south” and “west,” respectively. While“nautical miles” is shown in Table 2, any suitable unit includingmeters, kilometers, feet, or statute miles is included in aspects of thedisclosure. For example, nautical miles can be converted to variousstandard units wherein 1 NM is approximately equal to 1852 meters or6076 feet. It will also be understood that a latitudinal or longitudinalposition change in degrees can correspond to different error amounts innautical miles depending on the geographic location of the aircraft 10.

TABLE 2 First error X ₁ (81) −1.75 NM (N) −0.8 NM (E) Second error X ₂(82) −2.25 NM (N) −1.25 NM (E) Third error X ₃ (83) 5.0 NM (N) 2.5 NM(E)

It can be appreciated that the third error 83 is numerically larger thanthe first and second errors 81, 82. This larger error is visuallyrepresented in FIG. 2 as a larger arrow drawn from the first position 61toward the third preliminary solution 73 as compared to those drawntoward the first and second preliminary solutions 71, 72.

A set of statistical uncertainties can be related to at least some ofthe set of navigation parameters in 60, and can further be determined.The set of statistical uncertainties can be related to at least somenavigation parameters in the set of navigation parameters 60. Morespecifically, the set of statistical uncertainties can represent anuncertainty in the Kalman-filter-obtained errors 81, 82, 83 described inTable 2. Differences in error amounts can occur due to a variety ofcircumstances, such as miscalibration, measurement error, modelingerror, or sensor malfunction when obtaining the third position 63. Innon-limiting examples, the set of statistical uncertainties can bedetermined or computed by hand, by the flight management system 28, bythe flight control computer 22, or by any other suitable aircraft system20, or the like, or any combination thereof.

Table 3 below represents one non-limiting example of such a set ofstatistical uncertainties computed for each of the errors in Table 2.The set of statistical uncertainties is given below in the form ofcovariance matrices referenced to the IRS 40 reference frame, in unitsof feet-squared.

TABLE 3 First uncertainty P ₁ ^(pos) $\begin{bmatrix}640000 & 17500 \\17500 & 490000\end{bmatrix}\mspace{11mu}{ft}^{2}$ Second uncertainty P ₂ ^(pos)$\begin{bmatrix}722500 & 15600 \\15600 & 360000\end{bmatrix}\mspace{11mu}{ft}^{2}$ Third uncertainty P ₃ ^(pos)$\begin{bmatrix}169000000 & 240000 \\240000 & 81000000\end{bmatrix}\mspace{11mu}{ft}^{2}$

It can be appreciated that the third uncertainty in Table 3 is largerthan the both the first and second uncertainties. Referring now to FIG.3, the set of statistical uncertainties given in Table 3 isschematically illustrated by the relative size of the markers used toindicate the preliminary solutions 71, 72, 73 on the coordinate system50. The triangle denoting the third preliminary solution 73 is muchlarger than the star or rectangle denoting the respective first andsecond preliminary solutions 71, 72. In addition, the rectangle denotingthe second preliminary solution 72 is larger relative to the stardenoting the first preliminary solution 71. Stated another way, therelative difference in visual size of the preliminary solutions 71, 72,73 indicates the amount of statistical uncertainty (e.g. a quantitative“value” measuring or representing absolute or relative certainty) intheir corresponding position errors, such as those representednumerically in Table 2 above. In the illustrated example, larger visualsizes of the preliminary solutions 71, 72, 73 correspond to largerstatistical uncertainties (e.g. reduced certainty or less certainty,compared with a smaller visual size), and smaller visual sizescorrespond to smaller statistical uncertainties (e.g. increasedcertainty as compared with a larger visual size). In this manner, theset of statistical uncertainties can be related to at least somenavigation parameters in the set of navigation parameters 60, such asthe corresponding positions 61, 62, 63.

A statistical weight can be associated to each of the positions 61, 62,63 based at least on the statistical uncertainties of theircorresponding preliminary solutions 71, 72, 73. For example, the thirdpreliminary solution 73 can be associated with a smaller statisticalweight due to its larger uncertainty relative to those of the first andsecond preliminary solutions 71, 72. The first preliminary solution 71can be given the greatest statistical weight due to its statisticaluncertainty being smaller than those of the second and third preliminarysolutions 72, 73. A statistical weight for one navigation parameter inthe set 60 can be based on multiple statistical uncertainties, such as ablend of all statistical uncertainties. Equation 1 below gives oneexemplary method of determining or computing a statistical weight,represented by an unbiased statistical weight K ₁ ^(pos) associated withthe first position 61:K ₁ ^(pos) =P ₂ ^(pos) P ₃ ^(pos)( P ₁ ^(pos) P ₂ ^(pos) +P ₂ ^(pos) P ₃^(pos) +P ₁ ^(pos) P ₃ ^(pos))⁻¹  (1)

Table 4 below provides some exemplary values for a set of dimensionlessstatistical weights associated with each of the first, second, and thirdpositions 61, 62, 63 based on the statistical uncertainties of Table 3.In non-limiting examples, the set of statistical weights can bedetermined or computed by hand, by the flight management system 28, bythe flight control computer 22, or by any other suitable aircraft system20, or the like, or any combination thereof. The set of statisticalweights is shown in Table 4 as a covariance matrix corresponding to eachof the first, second, and third positions 61, 62, 63 (FIG. 2). It can beappreciated that the third position 63 is associated with the smalleststatistical weight, as it is related to the largest statisticaluncertainty (Table 3).

TABLE 4 First weight K ₁ ^(pos) $\begin{bmatrix}0.529270 & {- 0.002371} \\0.001149 & 0.422401\end{bmatrix}\quad$ Second weight K ₂ ^(pos) $\begin{bmatrix}0.468729 & 0.002223 \\{- 0.001173} & 0.575041\end{bmatrix}\quad$ Third weight K ₃ ^(pos) $\begin{bmatrix}0.002001 & 0.000148 \\0.000023 & 0.002558\end{bmatrix}\quad$

A navigational solution 90 for the aircraft 10 (FIG. 1) can be formedbased on the set of navigation parameters 60, set of preliminarysolutions 70, associated set of statistical weights (e.g. table 4), acombination thereof, or the like. For example, the navigational solution90 can be in the form of a “blended” or “composite” positionrepresenting a combination of the first, second, and third positions 61,62, 63 (FIG. 2). In one example, the statistical weights described abovecan be associated to the positions when determining or computing thenavigational solution 90. More specifically, the navigational solution90 can be an optimized navigational solution based on the set ofstatistical weights. In non-limiting examples, the navigational solution90 can be determined or computed by hand, by the flight managementsystem 28, by the flight control computer 22, or by any other suitableaircraft system 20, or the like, or any combination thereof.

In the example of FIG. 3, the set of statistical weights is visuallyrepresented by the navigational solution 90 being plotted closer to thefirst and second preliminary solutions 71, 72 as compared to the third.More specifically, the navigational solution 90 is plotted approximatelyequidistant from the first and second preliminary solutions 71, 72 tovisually represent the associated first and second weights beingapproximately the same size. It will be understood that values being“approximately the same” as used herein will refer to such values notdiffering by more than a predetermined amount, such as by more than 10%in one example. In this manner, the preliminary solution having thesmallest associated statistical uncertainty can be assigned the greateststatistical weight when determining or computing the navigationalsolution 90.

The set of statistical uncertainties can be utilized to form an overalluncertainty for the navigational solution 90. For example, in a similarfashion to determining the navigational solution 90, the errors of Table3 can be combined or blended to construct the overall uncertainty of thenavigational solution 90. The navigational solution 90 is plotted as asolid circle on the coordinate system 50 in FIG. 3. The overalluncertainty corresponding to the navigational solution 90 is shown byway of the relative visual size of the navigational solution 90 comparedwith that of the preliminary solutions 71, 72, 73. It is contemplatedthat the navigational solution 90 can have a smaller overall uncertaintythan any of the statistical uncertainties corresponding to thepreliminary solutions 71, 72, 73. In addition, the navigational solutioncan be more accurate than any of the preliminary solutions 71, 72, 73,as illustrated by its relative proximity to the true position 65.

Referring now to FIG. 4, the aircraft 10 is illustrated flying along acurrent flight path 100. The display 21 is schematically illustrated inthe aircraft 10. During operation, the set of navigation parameters 60of the aircraft 10 can be collected from at least one of the sensor 26,GPS 30, IRS 40, the like, or a combination thereof (not shown in FIG. 4for brevity). As explained above, the set of statistical uncertaintiesrelated to at least some navigation parameters in the set of navigationparameters 60, such as the positions 61, 62, 63 can be determined. Theset of statistical weights can then be associated to the positions 61,62, 63 based on the set of statistical uncertainties. The navigationalsolution 90 can finally be formed for the aircraft based on at least theset of statistical weights.

The navigational solution 90 can be displayed on the display 21 orcommunicated to the flight management system 28. For example, anestimate of position uncertainty (EPU), an actual navigation performance(ANP), a required navigation performance (RNP), or any combinationthereof can be displayed on the display 21, or communicated to any orall of the flight control computer 22, the flight management system 28,or a suitable aircraft system 20. In one non-limiting example, theaircraft 10 or a subsystem thereof can include calculating, determining,comparing, or the like, the navigational solution 90 with othersubsystem data or calculations, and new data or calculations can begenerated or determined based thereupon. In yet another non-limitingexample, the operation, control, flight, or operational parameters ofthe aircraft 10 or a subsystem thereof can be modified, overwritten, orsuperseded based upon, or in accordance with, the navigational solution90.

It is contemplated that the navigational solution 90 can form an EPU oran ANP for the aircraft 10. For example, the RNP can represent a therequired navigation performance along a planned flight path 102 againstwhich the aircraft 10 is instructed to compare its actual position andmake any adjustments necessary. For example, the navigational solution90 forming the EPU can be compared to the RNP. If the EPU exceeds theRNP, an alert can be displayed on the display 21. In non-limitingexamples, such an alert can signal that the EPU has exceeded the RNP,provide a recommended course correction to bring the aircraft 10 back tothe planned flight path 102, prompt a pilot to perform a manual coursecorrection, or prompt a pilot to engage an automatic system to alter thecourse of the aircraft 10. In addition, the navigational solution 90 canbe automatically transmitted to a vehicle management system such as theflight management system 28 (FIG. 1) of the aircraft 10. In theillustrated example, the aircraft 10 is altered from its current flightpath 100 toward the planned flight path 102 based on the navigationalsolution 90.

Referring now to FIG. 5, a method 200 of operating the vehicle 1 isillustrated by way of the aircraft 10. At 202 the vehicle 1 can benavigated along a path, such as the current flight path 100 of FIG. 4.At 204 a set of navigation parameters of the vehicle 1, such as the setof navigation parameters 60, can be collected from at least one of asensor 26, a global positioning system 30, an inertial reference system40, or the like. At 206 a set of statistical uncertainties related to atleast some navigation parameters in the set of navigation parameters canbe determined (FIG. 3). At 208 a set of statistical weights (FIG. 3) canbe associated to the at least some navigation parameters based on theset of statistical uncertainties. A navigational solution, such as thenavigational solution 90, can be determined at 210 for the vehicle 1based on the set of statistical weights. At 212, the vehicle 1 can beoperated in accordance with the navigational solution 90. One example ofsuch operating can include displaying the navigational solution on adisplay, such as the display 21 (FIG. 4). Another example of operatingthe vehicle 1 can include altering a current path based on thenavigational solution 90.

It will be understood that any aspect of the method 200, including theflying at 202, the collecting at 204, the determining at 206, or theassociating at 208, can be performed by hand, by the flight controlcomputer 22, by the flight management system 28, by any other suitableaircraft system 20 or subsystem thereof, or the like, or combinationsthereof.

FIG. 6 illustrates a method 300 of operating the aircraft 10. At 302 theaircraft 10 can be navigated or flown along a flight path, such as thecurrent flight path 100 of FIG. 4. At 304 a set of navigation parametersof the aircraft, such as the set 60, can be collected from at least oneof a sensor 26, a global positioning system 30, or an inertial referencesystem 40. At 306, a set of preliminary solutions, such as the set ofpreliminary solutions 70, can be determined, including computed, via aKalman filter for the set of navigation parameters. At 308 a set oferrors, such as the set of errors 80, can be determined, includingcomputed, for the set of preliminary solutions as described in FIG. 3.At 310 a set of statistical uncertainties can be determined, via acovariance matrix, for the set of preliminary solutions based on the setof errors as described in FIG. 3. At 312 a set of statistical weightscan be associated to the set of preliminary solutions based on the setof statistical uncertainties. A navigational solution, such as thenavigational solution 90, can be formed at 314 by blending the set ofpreliminary solutions based on the set of statistical weights asdescribed in FIG. 3. At 316 the aircraft 10 can be operated inaccordance with the navigational solution 90 including, but not limitedto, displaying the navigational solution 90 the display 21 or alteringthe current flight path 100 for the aircraft 10 (FIG. 4).

It will be understood in either of the methods 200, 300 that, in oneexample, the set of preliminary solutions can be determined prior todetermining or computing the set of errors. The set of errors can bedetermined prior to determining the set of statistical uncertainties.The set of statistical weights can be associated to the set ofpreliminary solutions prior to forming the navigational solution.Determining or forming the navigational solution can further includedetermining an overall uncertainty as described in FIG. 3. In addition,the method 200, 300 can also include altering a current flight path ofthe aircraft 10, such as the flight path 100.

It will also be understood that the set of preliminary solutions can bedetermined for any or all of the navigation parameters in the set ofnavigation parameters of the aircraft. For example, the flightmanagement system on the aircraft can be configured to perform a dataintegrity check on the set of navigation parameters or discard anyentries determined to be spurious, such as from a malfunctioning sensor.Such a check can be performed prior to the determining of the set ofpreliminary solutions.

The above described aspects provide for several benefits, includingimproved navigation performance such as position and ground speedaccuracy. Forming a single blended navigational solution, (e.g. a singleblended position) from multiple independently-obtained navigationalparameters (e.g. position) provides for improved accuracy and reduceduncertainty compared to any of the individually-obtained navigationalparameters, even when such individually-obtained parameters have beenKalman-filter corrected.

In addition, a technical effect of the above described aspects is theprovision of a scalable method of aircraft operation or navigationacross multiple cockpit architectures. Some examples include a splitcockpit architecture having three IRS installations, a single-solutioncockpit architecture having two IRS installations, or an unmanned aerialvehicle having a single IRS installation. Where multiple IRSnavigational solutions or parameters may be provided on an aircraft,each parameter has its own associated uncertainty. The single blendedsolution accounts for the associated uncertainties and errors in theindividually-obtained navigational parameters and minimizes the overalluncertainty associated with the single blended solution.

To the extent not already described, the different features andstructures of the various aspects can be used in combination, or insubstitution with each other as desired. That one feature is notillustrated in all of the aspects is not meant to be construed that itcannot be so illustrated, but is done for brevity of description. Thus,the various features of the different aspects can be mixed and matchedas desired to form new aspects, whether or not the new aspects areexpressly described. All combinations or permutations of featuresdescribed herein are covered by this disclosure.

This written description uses examples to disclose the invention,including the best mode, and also to enable any person skilled in theart to practice the invention, including making and using any devices orsystems and performing any incorporated methods. The patentable scope ofthe invention is defined by the claims, and may include other examplesthat occur to those skilled in the art. Such other examples are intendedto be within the scope of the claims if they have structural elementsthat do not differ from the literal language of the claims, or if theyinclude equivalent structural elements with insubstantial differencesfrom the literal languages of the claims.

Various characteristics, aspects and advantages of the presentdisclosure may also be embodied in any permutation of aspects of thedisclosure, including but not limited to the following technicalsolutions as defined in the enumerated aspects:

1. A method of operating a vehicle, the method comprising:

-   -   navigating the vehicle along a path;    -   collecting a set of navigation parameters of the vehicle from at        least one of a sensor, a global positioning system, or an        inertial reference system;    -   determining a set of statistical uncertainties related to at        least some navigation parameters in the set of navigation        parameters;    -   associating a set of statistical weights to the at least some        navigation parameters based on the set of statistical        uncertainties;    -   determining a navigational solution for the vehicle based on the        set of statistical weights; and    -   operating the vehicle in accordance with the navigational        solution.

2. The method of any of the disclosed aspects, further comprisingdetermining a set of preliminary solutions based on the set ofnavigation parameters via a Kalman filter.

3. The method of any of the disclosed aspects, further comprisingdetermining a set of errors for the set of preliminary solutions,wherein each in the set of errors corresponds to a preliminary solutionin the set of preliminary solutions.

4. The method of any of the disclosed aspects wherein each in the set ofstatistical uncertainties corresponds to an error in the set of errors.

5. The method of any of the disclosed aspects wherein the set ofpreliminary solutions is determined prior to determining the set oferrors, wherein the set of errors is determined prior to determining theset of statistical uncertainties, wherein the set of statistical weightsis associated prior to determining the navigational solution, andwherein the determining the navigational solution further comprisesdetermining an overall uncertainty for the navigational solution.

6. The method of any of the disclosed aspects wherein the determiningthe navigational solution comprises blending the set of preliminarysolutions via the Kalman filter.

7. The method of any of the disclosed aspects wherein the set ofpreliminary solutions comprises at least one of a current position or acurrent velocity of the vehicle.

8. The method of any of the disclosed aspects wherein the navigationalsolution comprises an optimized navigational solution based on the setof statistical weights.

9. The method of any of the disclosed aspects wherein the set ofnavigation parameters comprises at least one of a position, a velocity,a heading, or a reference frame.

10. The method of any of the disclosed aspects wherein the operatingfurther comprises displaying at least one of an estimate of positionuncertainty, an actual navigation performance, or a required navigationperformance.

11. The method of any of the disclosed aspects, further comprisingcomparing an estimate of position uncertainty to a required navigationperformance, and wherein the displaying comprises a displayed alert whenthe estimate of position uncertainty is greater than the requirednavigation performance.

12. The method of any of the disclosed aspects, further comprisingautomatically transmitting the navigational solution to a vehiclemanagement system.

13. The method of any of the disclosed aspects, further comprisingaltering a current path based on the navigational solution.

14. A method of operating an aircraft, the method comprising:

-   -   navigating the aircraft along a flight path;    -   collecting a set of navigation parameters of the aircraft from        at least one of a sensor, a global positioning system, or an        inertial reference system;    -   determining a set of preliminary solutions for the set of        navigation parameters by applying a Kalman filter;    -   determining a set of errors for the set of preliminary        solutions;    -   determining, via a covariance matrix, a set of statistical        uncertainties for the set of preliminary solutions based on the        set of errors;    -   associating a set of statistical weights to the set of        preliminary solutions based on the set of statistical        uncertainties;    -   forming a navigational solution for the aircraft by blending the        set of preliminary solutions based on the set of statistical        weights; and    -   operating the aircraft in accordance with the navigational        solution.

15. The method of any of the disclosed aspects wherein the set ofpreliminary solutions comprises at least one of a position of theaircraft or a velocity of the aircraft.

16. The method of any of the disclosed aspects wherein the forming thenavigational solution further comprises determining an overalluncertainty for the navigational solution based on the set ofstatistical weights.

17. The method of any of the disclosed aspects wherein the overalluncertainty comprises an estimate of position uncertainty for theaircraft.

18. The method of any of the disclosed aspects wherein the displayingfurther comprises displaying at least one of an estimate of positionuncertainty, an actual navigation performance, or a required navigationperformance.

19. The method of any of the disclosed aspects, further comprisingcomparing an estimate of position uncertainty to a required navigationperformance, and wherein the displaying comprises a displayed alert whenthe estimate of position uncertainty is greater than the requirednavigation performance.

20. The method of any of the disclosed aspects, further comprisingaltering a current flight path based on the navigational solution.

What is claimed is:
 1. A method of operating a vehicle, the method comprising: collecting a set of navigation parameters of the vehicle from at least one of a sensor, a global positioning system, or an inertial reference system; applying a correction to each navigation parameter in the set of navigation parameters to determine a corresponding set of preliminary navigational solutions; determining a statistical uncertainty corresponding to each preliminary navigational solution in the set of preliminary navigational solutions to define a set of statistical uncertainties; associating a statistical weight to each navigation parameter in the set of navigation parameters, based on the set of statistical uncertainties, to define a set of statistical weights; blending the set of preliminary navigational solutions, based on the set of statistical weights, to determine a single navigational solution for the vehicle; and operating the vehicle in accordance with the single navigational solution.
 2. The method of claim 1, wherein the applying the correction is performed via a Kalman filter.
 3. The method of claim 2, further comprising determining a set of errors for the set of preliminary navigational solutions, wherein each error in the set of errors corresponds to a preliminary navigational solution in the set of preliminary navigational solutions.
 4. The method of claim 3 wherein each statistical uncertainty in the set of statistical uncertainties corresponds to an error in the set of errors.
 5. The method of claim 4 wherein the set of preliminary navigational solutions is determined prior to determining the set of errors, wherein the set of errors is determined prior to determining the set of statistical uncertainties, wherein the set of statistical weights is associated prior to determining the single navigational solution, and further comprising determining an overall uncertainty for the single navigational solution.
 6. The method of claim 2 wherein the set of preliminary navigational solutions comprises at least one of a current position or a current velocity of the vehicle.
 7. The method of claim 1 wherein the single navigational solution comprises an optimized single navigational solution based on the set of statistical weights.
 8. The method of claim 1 wherein the set of navigation parameters comprises at least one of a position, a velocity, a heading, or a reference frame.
 9. The method of claim 1 wherein the operating further comprises displaying at least one of an estimate of position uncertainty, an actual navigation performance, or a required navigation performance.
 10. The method of claim 9, further comprising comparing an estimate of position uncertainty to a required navigation performance, and wherein the displaying comprises a displayed alert when the estimate of position uncertainty is greater than the required navigation performance.
 11. The method of claim 1, further comprising automatically transmitting the single navigational solution to a vehicle management system.
 12. The method of claim 1, further comprising altering a current path based on the single navigational solution.
 13. A method of operating an aircraft, the method comprising: collecting a set of navigation parameters of the aircraft from at least one of a sensor, a global positioning system, or an inertial reference system; applying a correction, by way of a Kalman filter, to each navigation parameter in the set of navigation parameters to determine a corresponding set of preliminary navigational solutions; determining a set of errors for the set of preliminary navigational solutions; determining, by a covariance matrix, a statistical uncertainty for each error in the set of errors to define a set of statistical uncertainties; associating a statistical weight to each navigation parameter in the set of navigation parameters, based on the set of statistical uncertainties, to define a set of statistical weights; blending the set of preliminary navigational solutions, based on the set of statistical weights, to determine a single navigational solution for the aircraft; and operating the aircraft in accordance with the single navigational solution.
 14. The method of claim 13 wherein the set of preliminary navigational solutions comprises at least one of a position of the aircraft or a velocity of the aircraft.
 15. The method of claim 13, further comprising determining an overall uncertainty for the single navigational solution based on the set of statistical weights.
 16. The method of claim 15 wherein the overall uncertainty comprises an estimate of position uncertainty for the aircraft.
 17. The method of claim 13 wherein the operating further comprises displaying at least one of an estimate of position uncertainty, an actual navigation performance, or a required navigation performance.
 18. The method of claim 13, further comprising comparing an estimate of position uncertainty to a required navigation performance, and wherein the operating comprises a displayed alert when the estimate of position uncertainty is greater than the required navigation performance.
 19. The method of claim 13, further comprising altering a current flight path based on the single navigational solution. 